Campaigners opposed to the expansion of Bristol International airport claim the move will produce greenhouse gases and harm the countryside. Under current plans the number of people using the airport is likely to double over the next 25 years.
The Stop Bristol Airport Expansion group has joined a protest calling for an urgent rethink of government policy.
In response, Bristol International airport said it took environmental responsibilities "very seriously".
Environmental 'impact'
Andrew Skipp, managing director of Bristol International Airport, said: "We'll never be at the size of Heathrow or Gatwick but what we do want to do is make it so that local people can fly locally."
He said they wanted to avoid a situation in which travellers had "three, four or five hour journeys with all the disadvantages that has for the environment".
Air travel contributed less than half of 1% of the South West's total greenhouse emissions, added Mr Skipp.
Local resident Tony Watts is strongly opposed to the airport's expansion and said: Everything we do as citizens to try to reduce our impact on the environment is a complete waste of time because the airport is going to expand at such a rate that they will undo all that hard work."